Process foe treating petroleum



May 14, 1935. R. CROSS PROCESS FOR TREATING PETROLEUM HYDROCARBONS Original Filed Aug. 2, 1924 Reissued May 14, 1935 PROCESS FOB. TBEATING PETROLEUM HYDBOCAB-BONS A Boy Gross,v Kansas City, Mo., assigner, by assignments, to Gasoline Products Company,

Inc., Wilmington, Del., a corporation of Delal f Original No. 1,775,067, dated September'v 2, 1930,

Serial No. 729.693, August 2, 1924. Applica- .tion for reilue August 31, 1932, Serial No.

Thil inventim relates to improvements in a prono and apparatus for treating petroleum lw'drorbons and refers more particularly to a us method of cracking hydrocarbons v, contini czto'zykid relatively light distillate having the of gasoline and the like-the taking place under relatively and while the on is maintained in the liquid phase.

10:: img'the salient objects of the invention are,

termico a process in which petroleum hydroare continuously treated in a system under relatively high pressure whereby a, synthetio crude is formed in which are contained 1I3 Mailly more of the low boiling point or 'aetidls than in the original charging mixto' provide a process in which this synihetiocrudowhile at high temperature is revlolliliroln tho-lone of high pressure whereby 20:. the liditer fractions are distilled off: to provide aproooas in which these lighter fractions are sublflllontly subiected 'to reflux condensation and aprooess in which the liquid material separated @t Ming the refluxing or dephlegmating of the Y 25: mi is returned to either the evaporatlng stage or ,the initial stage of redux condensation in order-.t0 extract the gasoline fractions out of the residuo. or bottoms separated in the nal stage .Mlegmation; to provide a process in which 30.", an meedyield o! gasoline distillate is promund and me in which there is an increased vill o! heat primarily due to the method of conversion and the recycling of the products for rediltillatiomand, in general, to provide an ap- 351m for carrying out the process hereinafter In e drawing. the single gure is a diagrammatlcside elevational view of the apparatus with lecion and parts broken away. to thedrawln, at i is showna haringen upper and lowerA compartupper compartment containing the -A v 2 and the lower compartment of heating tubes t which are connected 4N lille l. The furnace is preferably W by means of a gas burner diagrammaticalli,l wn at I. The element 6 is a reaction eonnectedbyatransferlinel tothe Y end of the heating coil and with the so 2 by means of the transfer line 9 in the reduction valve It. The lt il is l.` baille type of dephlegmating or tower connected to the evaporator by a vapor line I2 and with the bubble The top of the e so? my by a vapor line Il.

2 claims. (ci. 19e-4s) bubble tower communicates through a line It to the condenser coil i6 positioned in the coridenser box I'I. At I8 is shown a gas separator, connected with the discharge end of the condenser coil i6 by means of a' valve Il and with the receiver 20 through the pipe 2|. 22. 23 and 24 are storage tanks for gasoline distillate. recharging stock and fuel oil respectively. At 25 is shown a cooling coil for reducing the temper-l ature of the bottoms withdrawn fromrthe lower part of the tower Il through the automatically operated valve 26 and line I1. The element 28 is a cooling coil through which is circulated the fuel oil bottoms or residual hydrocarbons' withdrawn automatically from the lower part of the evaporator 8 through the valve 29 and line 20. At 3l, on the side oi each of the towers, is diagrammatically shown a liquid level regulating device for controlling the level in the respective towers by automatic manipulation of the valves 26, 29 and 22. l

Referring now to the operation, the oil to be treated is Qharged from the tank 23 to which it is introduced from any convenient source. This charging stock may consist of hydrocarbons such as those commercially known as kerosene, gas oil or fuel oil, or any type of hydrocarbons utilised in a cracking system for the production of gasoline distillate. This oil is withdrawn from the tank 22 through the line 28 and is charged, by means of the pump 34, through the line 26, preheating tubes 2 and heating tubes 3, successively.

The oil, after passing through the heating tubes where it is subjected to cracking temperatures. is passed continuously through the line 1 into the reaction chamber where it is permitted to collect in a considerable body and remain for a sufficient period of time for the cracking reaction, which is initiated in the coil. to be completed. The heating ofthe oil in the coils is so controlled that while the oil is heated to a cracking temperature. no substantial conversion lis permitted to take place-thus eliminating the deposition of free carbon in the coils and concentrating carbon deposition in the reaction chamber. The reaction chamber is preferably of forged steel construction in` order to withstand the high pressures to whichit is subjected. As previously stated, the temperature and'pressure conditions are so regulated to cause the cracking to take place substantially in the liquid phase in the reaction chamber. Thus the hydrocarbons, on being withdrawn from the chamber, are in the form of a liquid synthetic crude having an increased per-- centage oi' low boiling point or lighter fractions relative to the charging stock. `This synthetic conditions it may be advantageous to introduce steam, or a liquid medium either cooler or at a higher temperature than the oil, throughy the line 36 controlled by a valve 31. Such conditionsa're present where an excessive amount of oilis iis` tilled olf with the reduction of pressure, leaving only a dry coke which is d lihcult to rcmovenfrom the evaporating tower. Under such conditions,

the introduction of a cooler hydrocarbon, or cool-` er medium, serves to reduce thetemperature of the oil and increase the liquid fresidual material formed in the evaporator. The' introdilc'tionofy steam, at this point, assists and promotes vaporization of the synthetic product and improves the character of the nal distillate.

' The' vapors disc-lied on' lathe evaporatmg tower pass overhead through the line I2 andare introduced intothe bottom of the reflux or dephlegmating tower IIv in which may -be positioned baite elements, such as those shown at 38, or

. ihert packingmaterial, such asRaschig rings or they like. Inthis tower` are yseparated out the hlh* boiling point fractions which are drawn of! as previously explained through the vline 21, cooling fcoil25 and connecting line`39 which conducts them tothe recharging stock `tank 23 where* theyv are recycled with the incoming fresh charglng `stool: `hack to the vcranking system. f

The micondensed fractions, passing out of the top-of the column I I, are introduced by means of the line I4 into the bottom of the bubble to'w'erA lwhere a further separation is effected'due to the contacting of these vapors with the separate pools o1 oil maintained at intervals 'in the column through which they are caused Ito pel-colate. The liquid condensed from the vapors is drained back in an opposed direction to their travel and is collected in the bottom of the tower. Thestill uncondnsed material passes off through the line lif'and is vsubiecteci to a condensing action in the coil yIl whereaiterit is passed through theV gas sepfrator I8, liquid` receiving ftank 20 and finally into thega'soline storage tank 22. The gas seprated from thellquld at la is returned throughl the line?" controlled by a valve 4I and `is utilized asfiiel inthe burners 5 in theiurnace I.

The method o! operation, to this point, is substantially the same as the process described in certain prior applications with the possible ex caption that anA additional dephleglnating towery is interposed between the bubble tower and the evaporating tower. The present invention differs from the prior applications, and principally application Serial No. 701,283, filed `March 24th,

. 1924-, inf thnme OfWalter M. Cross, 1n that the liquid bottoms separated out in the dephlegmating tower Il in place oi' being returned directly to the cracking system through the charging line for treatment in the heating tubes, is recycled when drawn of! through the valve 32 and pipe 42 to a return pump 48 by means of whichthis reiiuxcondensate may be directed to the evaporat- Q ing tower through `the pipe 4l controlled by a` valve orf bymanlpulation of 1the valve I5 and the valve 48 diverted into the tower II through the line l1; By returning the renux material back in the bubble tower to the evapora'tor orto` the first' stage of dephlegmation, lt ikpossible to reboil or redistill these relatively ilghterfmcmns wlthwt the necessltyof recu-- culation through `the heating system. It is a well known fact that the products separated out in this final stage, or bubble tower I3, are relatively close in their boiling pointk characteristics to the gasoline distillate finally recovered ami require very little additional heat for redistillation. Thus the recirculation through the two preceding stages yor through either stage, furnishes a means for retreating. thse fractions without the necessity of intermlngling them with oils of a radically different character, such Vas the irst charging stock or recharging stock withdrawn from the initial tower il: This method of treatment gives not only increased yields, but improves the charactor of the distillate in thatthe boiling point range is considerably reduced. A further advantage of returning this material to the evaporating tower, is that it assists to prevent coking of the fuel'oil or residual material in the evaporating tower. y

A typical operation on midhcontinentgasil of` from 30 to 32B."gravity, yieldodiin emessi of forty percent (40%) distillatef-f-tonipratiitesf from 700 to 850 F. being maintained inithore'# action chamber and.y pressures infeluiess-offaoI atmospheres. The temperatures ln the cvapolfaiiiMIU ing tower range from 650 toy 725 Firth@ perature in the initial tower II approximately 600 F., While the temperature in thlwlfltt* of the' bubble tower was in the neighborhood of 450? Thus; it isobvious that the condensator from the. bubble tower could be readily retreatsl ed inveither oi the preceding stages." L Iclaim: i i f 1. Ay process` for treating petroleum'. l'lydi'tlciil1 bon oils comprising heating the oi-lsto a'craciliirig' temperature in a heating stage without ariyisub stantial vaporization thereof' andbefore' stantial decomposition occurs, passing'tho heatotil oil to a digestion stage where tlle'cracliiigL in-` itiated in the heating stage is substantiallyfeon summated and wherein'theoil is maintained 'sub stantially in liquid phase, reducing the pressure and distilling oil' thev lighter fractionsA la" evaporating stage, subjecting the vaporized prod# ucts to a dephlegmating action in separatesucl-v4 cessive stages and to a `nal condensing action; optionallylrecycling the reflux condensatelitem the final dephlegmating stage tothe condensatevinthe bottom of the preceding dephiegmlmng; stage. to distill oil the remaining llgl'ltiir frac-v tions or recycling `the reflux condensate fromthe nal dephlegmating stage tothe oil inthe bottom of the evaporatfin'g s`t'agllto'a'ea4 sist in preventing coking ofthe unvaporizellfoli; and recycling reflux condensate remaining` vapor-ized in the initial rdephlegiii'lajzlhgL stage through the system. f I* 2. In a process for converting higher hydrocarbons into `le'vwei" boiling suitablefor motor fuel saidlghelfbil# ing hydrocarbons are' subjected lul temperature whilev maintained Jat relatively high? superatmospheric pressure h'a for a perluarsumclent to' elrectr the deslrseml; version thereof'and the converted products at elevated temperature are passed 'toalv'apoiv lng zone maintained underpressurelsifcciesuy' lowerfthan that `lnair'ltaiiled in saidy zone to normally cause substantially all vertes products to vmaman luto paseos easy coke dificult to rmve; th inprovhihii comprises fractionally 'condensing vopors-ili ated in said vaporizlng zone, sesporiitely4 comet-f mc a heavy conuellsaterrasuon, anonieme@ 'w1 ate te fraction, and a. light final consaid vaporizing zone at l. substantially constant denllte fraction. and introducing intermediate rate sufiicient to prevent the accumulation of condenan so obtained into said vaporizins zone large quantities of fuel oil therein, and returnin an amount sumcient to prevent vaporization ing said heavy condensate to said conversion 5 of the heavy liquid constituents of said conzone. vetted products and produce s liquid residue suit- ROY CROSS. able for fuel oil. withdrawing said fuel oil from I 

